An estimated ten (10) million adults suffer from chronic back pain, a condition that can limit their activities. Many adults with back pain undergo traditional spine surgery, which can require months of recovery.
For quite some time, lumbar spinal fusions have been performed for a variety of spinal conditions, such as posterior, posterolateral and anterior lumbar interbody fusions, to alleviate back pain.
Lumbar spinal fusion is a common technique to help patients with back pain, who have generally been unable to alleviate their back pain with non-operative treatment. Once a patient and their physician have decided to fuse at least two vertebrae in the lumbar spine, one of a variety of procedures may be selected. The choice of technique may be dependent on the patient's specific condition or it may be predicated upon surgeon preference regarding a surgical approach to the spine, for example, the front of the spine (anterior), the back of the spine (posterior) or less invasive approaches, called Minimally Invasive Spinal (MIS) surgery. The goals of all these techniques remain the same, to achieve a lumbar fusion, and lessen the patient's pain.
The most common method of spinal fusion involves the posterior approach, with an incision along the back of the patient's spine. Often, this procedure is used if bone spurs, thickened ligaments, or disc ruptures are removed to alleviate pressure on the nerves. The fusion procedure then typically involves placement of metal screws, rods and bone graft.
Anterior spinal fusions require an incision through the abdomen. After removal of the degenerated disc, an intervertebral implant such as a metal cage, spacer, or the like alone or in combination with a bone graft is usually placed in an intervertebral disc space between vertebral bodies.
Posterior approaches may include posterior and transforaminal lumbar interbody fusions, whereas anterior techniques may include retroperitoneal and transperitoneal anterior lumbar interbody fusion approaches. At times, patients may undergo both anterior and posterior procedures.
In order to achieve adequate exposure to perform posterior and anterior procedures, an open surgical approach is traditionally performed.
As an alternative to an open surgical approach, MIS surgery techniques for lumbar fusions have been developed. MIS procedures typically have smaller incisions, may limit trauma to the surrounding tissues and may result in a faster recovery for the patient. One of these MIS techniques is a procedure that may be referred to as an extreme-lateral lumbar interbody fusion (XLIF). During the XLIF procedure the lumbar spine is typically approached from the side through a small skin incision. The surgery is performed through a muscle that lies next to the lumbar spine known as the psoas muscle, thereby avoiding the disruption of muscles and tissue in the anterior or posterior of the spine that the surgeon traditionally has had to go through to access the spine.
With the XLIF procedure, the incisions are typically smaller than those in traditional back surgeries, which generally results in minimal tissue disruption and shorter hospital stays and recovery time. For example, a patient may spend one night in the hospital compared to the five nights is some traditional surgery patients.
XLIF procedures may also be performed in combination with nerve avoidance technology. When performing the XLIF surgery with nerve avoidance technology, surgeons may be able to gain access to the spine with direct visualization, avoid nerves and stabilize the spine, while generally using traditional techniques. The technology allows surgeons to perform procedures through a minimally invasive approach. Additionally, the doctors can perform surgical procedures using instruments that are similar to those used in open procedures, but through potentially smaller incisions, while still allowing for maximum surgical access to the spine for addressing the pathology and inserting an intervertebral implant.
However, the XLIF procedure is generally contraindicated for the L5-S1 intervertebral disc space given the lumbar and sacral transitional anatomy. Discectomies associated with the L5-S1 space generally involve the mounting of various surgical instruments, such as a mounting bracket, onto support structure external to the patient, such as the guiderail of a patient support structure, a bed, a table, a gurney, or the like. Additional surgical apparatus, such as a retractor and the like, are supported by the mounting bracket for lateral access into the L5-S1 intervertebral disc space. Movement of the patient relative to the guiderail or external support structure can impact the alignment of the surgical instruments relative to the target intervertebral disc space.
It is desirable to develop a method and apparatus for accessing an intervertebral disc space, such as the L5-S1 intervertebral disc space, from a lateral approach angle wherein movement of the patient has little or no impact on the orientation of the instruments relative to the patient.